Iran nuclear sites may be beyond reach of ‘bunker busters’
Only US able to mount credible conventional raid • New behemoth bomb shores up US threat plausibility
LONDON (Reuters) – With its nuclear program beset as never before by sanctions, sabotage and assassination, Iran must now make a new addition to its list of concerns: One of the biggest conventional bombs ever built.
Boeing’s 30,000-pound Massive Ordnance Penetrator (MOP), an ultra-large bunker buster for use on underground targets – with Iran routinely mentioned as its most likely intended destination – is a key element in the implicit US threat to use force as a last resort against Iran’s nuclear ambitions.
The behemoth, carrying more than 5,300 pounds of explosives, was delivered with minimal fanfare to Whiteman US Air Force Base in Missouri in September. It is designed for delivery by B-2 Stealth bombers.
The question is: Would that weapon, delivered in a gouging combination with other precision-guided munitions, pulverize enough rock to reach down and destroy the uranium enrichment chamber sunk deep in a mountain at Fordow, Iran’s best sheltered nuclear site?
While the chances of such a strike succeeding are slim, they are not so slim as to enable Tehran to rule out the possibility of one being attempted, according to defense experts contacted by Reuters.
A “second best” result might be merely to block the plant’s surface entrances, securing its temporary closure, some said.
One US official, speaking to Reuters on condition of anonymity, described an attack on the underground site, about 160 kilometers south of Tehran near the Iranian holy city of Qom, as “hard but not impossible.”
The United States is the only country with any chance of damaging the Fordow chamber using just conventional air power, most experts say.
Israel, the nation seen as most likely to attempt a raid, has great experience in longrange bombing, including its 1981 raid on the Osirak nuclear reactor in Iraq and a 2007 strike on a presumed nuclear facility in Syria.
But it lacks the air assets to reach Fordow’s depths, and has no Mop-sized bunker buster. An Israeli raid would therefore likely require other elements, such as sabotage or special forces.
The vulnerability of the chamber at Fordow, believed to be buried up to 80 meters deep on a former missile base controlled by the elite Revolutionary Guards Corps, came into sharper focus on Monday when the UN nuclear watchdog confirmed that Iran had started enriching uranium at the site.
The same day a State Department spokeswoman declared that if Iran was enriching uranium to 20 percent at Fordow this would be a “further escalation” of its pattern of violating its obligations under UN Security Council resolutions.
Western powers suspect the program is aimed at developing the capacity to build a nuclear weapon. Iran says it is strictly for civilian uses.
Critics of Iran’s nuclear program tend to agree that military action against Iran’s nuclear work would be their last, and worst, option. Not only would this risk civilian casualties, but Iran would seek to retaliate against Western targets in the region, raising the risk of a regional war and global economic turmoil.
Once it had recovered it would probably decide unequivocally to pursue a nuclear bomb.
Critics of the military option further point out that non-military pressure is increasing. Apart from tools of statecraft such as sanctions and diplomacy, covert means against Iran’s nuclear work probably include sabotage, cyber attacks, measures to supply Iran with faulty parts and interception of nuclear supplies.
It may also involve assassinations of nuclear experts, such as Wednesday’s killing of a scientist in Tehran.
A strike, furthermore, would only delay, not destroy, an Iranian nuclear program whose known sites are widely dispersed and fortified against attack.
But Washington sees the plausibility of a US strike on Iran’s main nuclear sites as a vital adjunct to the campaign of pressure. The narrow, technical question of whether such an attack is feasible is therefore central to strategy.
“You don’t take any option off the table,” US Defense Secretary Leon Pannetta said on CBS’S Face the Nation television program on January 8.
Asked on the same program how hard it would be to “take out” Iran’s nuclear capability, US Chief of Staff Gen. Martin Demspey said: “Well, I’d rather not discuss the degree of difficulty and in any way encourage them to read anything into that. But I will say that our – my – responsibility is to encourage the right degree of planning, to understand the risks associated with any kind of military option, in some cases to position assets, to provide those options in a timely fashion. And all those activities are going on.”
Asked if the US could act against Iran’s nuclear capability using conventional weapons, he replied: “Well, I certainly want them to believe that that’s the case.”
The credibility of that implicit threat got a freshening-up with the arrival of the big new bomb in the US arsenal.
Military satisfaction was evident.
As Brig.-gen. Scott Vander Hamm explained to the online Airforce Magazine, the MOP “is specifically designed to go after very dense targetssolid granite, 20,000 [pounds per square inch] concrete, and those hard and deeply buried complexes –where enemies are putting things that the President of the United States wants to hold at risk.”
He said MOP “kind of bridges the gap” between conventional munitions and nuclear weapons in terms of the effects that it can create. Whereas in the past, “you’d have to break that nuclear threshold” to attack such HDBT (hard and deeply buried targets), “with the MOP, you don’t have to,” the magazine reported.
Four months on from the bomb’s arrival in the US arsenal, the Fordow announcement has sharpened the Western strategic focus on US military capacity.
Experts differ on the extent of the challenge at Fordow, but all agree it presents greater complexity than Iran’s other underground site at Natanz, 230 km. south of Tehran, where enrichment happens in a chamber estimated to be 20 meters underground, or less than a third of Fordow’s presumed depth.
The other likely targets are Iran’s uranium-ore-processing plant at Isfahan, some 400 km. south of Tehran and plutonium producing research reactor under construction at Arak, 190 km. southwest of Tehran. They are both above ground and considered vulnerable to attack.
Austin Long, an assistant professor at the School of International and Public Affairs at Columbia University, told Reuters the arrival of the MOP “does not solve the Fordow problem, but it does make it easier.” Many experts are skeptical. Mark Fitzpatrick, an Iran expert at London’s International Institute for Strategic Studies, said that Natanz was buried under several layers of dirt and concrete but it was “nevertheless possible to damage it with precision bombing with one sortie to create a crater and second sortie to burst through the bottom of the crater to the facility below.”
But the chamber at Fordow might be “impenetrable,” he said, due to its presumed depth.
Sam Gardiner, a retired USAF colonel who runs war games for various Washington agencies, told Reuters a major problem was simply a lack of confirmed information about the Fordow plant.